Birds on a train, goats on a bus—see some weird ways animals get around.

From birds on a train to goats on a bus—adaptable animals are learning how to get around our expanding cities.

Many are domestic—like cats—but coyotes, monkeys, and other wild species are also finding their way onto public transportation.

These animal "commuters" are motivated more by food and security than anything else, said Suzanne MacDonald, a psychologist and biologist at York University in Toronto, Canada, who studies urban wildlife.

"If they're sitting there thinking, 'I gotta catch that 3 o'clock bus in order to make it to the movies,' then we're in deep doo-doo," quipped MacDonald, who receives funding from the National Geographic Expeditions Council.

Instead, animals that end up on buses or trains usually realize "if they get on this thing and get off this thing, in between they [can be] treated pretty well and rewarded for it."

Indeed, urban-wildlife ecologist Seth Magle noted that many animals drawn to public transportation are likely getting fed by people, which should be avoided.

"It seems cute, but it's an opportunity where people can come into conflict with animals," said Magle, who directs the Lincoln Park Zoo's Urban Wildlife Institute.

"But being pigeons, they do not listen for the announcement that the train is leaving, and the doors close on them. They ride generally for one stop, exiting as soon as the doors open again," the Times reported.

But they're not total bird brains: The article reported that a train conductor would see them promptly fly back to the Far Rockaway terminal for more free food. (See National Geographic's bird pictures.)

Take Macavity, the kitty who would get on a busy bus at the same stop in Walsall every morning, and then jump off at the next stop not far down the road—which just happens to be near a fish-and-chip shop, the Daily Mail reported in 2007.

"I suppose he is the perfect passenger really—he sits quietly, minds his own business, and then gets off," passenger Paul Brennan told the paper.

Then there's Casper the commuter cat, which BBC News reported in 2009 was a regular on a bus near its home in St. Budeaux, England. Sadly, Casper died in 2010 after being hit by a car while crossing the road to board the bus, according to the Daily Mail.

A commuting feline named Dodger liked to sit in laps as he rode the bus around Dorset, England, the Daily Mail reported in 2011. His owner suspects the cat was attracted to the warmth of the bus and recently vacated seats.

MacDonald noted that domestic animals like cats are likely more comfortable hopping on buses because they're used to people—but that it's still "amazing" they're not stressed by the riding experience.

The emboldened animals have also overrun parts of the city. According to the Times, the animals "treat the Indian Parliament building as a playground, have invaded the prime minister's office and Defense Ministry, sometimes ride buses and subway trains, and chase diplomats from their well-tended gardens."